Toughness and microstructural analysis of superduplex stainless steel joined by plasma arc welding

EN 1.4410 (UNS S32750) superduplex stainless steel (SDSS) with a thickness of 6.5 mm has been welded by plasma arc welding (PAW) process with different heat inputs. To determine the mechanical properties, impact toughness testing at subzero temperatures starting from −20 °C down to −60 °C was carried out while fractographs were examined by scanning electron microscopy (SEM). Microstructural examination included macro- and microphotographs of the cross sections, ferrite content measurements and hardness survey of the weld zones. Interpreting all data obtained, results were compared depending on the heat inputs of the joints while the relation between heat input and properties was explained. Promising low temperature toughness, results were obtained while it was concluded that the variation of the heat input influenced mainly the ferrite content and hardness of the weld zones. Results showed that PAW, which is considered immature process in welding of SDSS, can be employed for 1.4410 superduplex grade with controlled heat input so the properties.